0159 LABORATORY-BASED SLEEP RESTRICTION ENHANCES THE CORTISOL AWAKENING RESPONSE IN HEALTHY ADULTS

Abstract

Sleep restriction is related to risk for stress-related symptoms and disease processes. The cortisol awakening response (CAR) is the increase in cortisol observed immediately post-awakening in the morning. CAR is an indicator of an individual’s readiness to maintain alertness and psychological function in response to demands of the upcoming day. CAR is affected by insufficient sleep, though the direct effect of extended sleep restriction on CAR is not known. We examined profiles of CAR of healthy good-sleeping young adults in response to extended moderate sleep restriction and subsequent sleep recovery. Healthy participants [N=48; M(SD) age: 25.4(3.9); 39.4% Female] underwent sleep satiation (5 nights/10h time in bed [TIB]), extended sleep restriction (5 nights/5 h TIB; 0200-0700), and sleep recovery (3 nights/8h TIB). Salivary cortisol was collected 5-, 30-, and 45-minutes post-awakening following sleep satiation (baseline), and every morning following sleep restriction and recovery evenings. CAR was quantified using area under the curve relative to ground (AUC-G). Linear mixed effects models were used to examine baseline-to-sleep restriction and baseline-to-recovery AUC-G trends. AUC-G increased linearly from baseline across sleep restriction (b=.06, SE=.02, t=2.8, p=.007), and remained elevated relative to baseline following the sleep recovery (b=.03, SE=.01, t=2.4, p=.02). Model fit was not improved including age and sex as covariates. Increased CAR across the restricted sleep period supports the notion that the CAR may represent an adaptive response to restricted sleep associated with arousal and anticipation to meet the demands of the upcoming day. We also observed a lack of recovery to baseline following 3 nights of recovery sleep. While acute increases in CAR may be related to the ability to effectively cope with the demands of a day following sleep loss, more prolonged or chronic sleep restriction and concurrent elevations in CAR may be related to health-compromising hypothalmic-pituitary-adrenocortical (HPA) function. Department of Defense Military Operational Medicine Research Program (MOMRP).